The present invention concerns improvements to pushchairs of the type having a chassis which is born upon one or more primary wheels on a primary wheel bearing axis.
The present Applicant""s earlier UK Patent GB 2265341 describes a type of pushchair which has its chassis born upon one or more primary wheels on a primary wheel bearing axis and having forward and/or rear secondary wheels or stabilizers that in normal use of the pushchair are not ground engaging. The chassis and as seat for the child are arranged to place the center of gravity of the occupied pushchair at or near to the primary transverse axis, comprising an axle or coaxial series of axles. To which the main wheel or wheels are mounted. The secondary wheels or stabilizers are configured to have ground clearance of several centimeters when the pushchair is balanced over the primary axis. When the pushchair is at rest either the front or the rear secondary wheel(s) or stabilizers is/are in ground contact but the other is clear of the ground. The function of the secondary wheels or stabilizers is to assist in curb climbing and to provide additional stability, limiting excessive tilting about the primary axis.
The center of gravity of the pushchair is located in this distinctive way partly in order that the user benefits from the greater mechanical efficiency of balancing on centralized large main wheel(s) compared with the spread out relatively small wheels of conventional pushchairs. The configuration also brings substantial advantages when turning. The balancing of the weight of the pushchair over the main wheel(s) greatly facilitates maneuvering.
Although the design brings significant advantages in use and although the pushchair does have the secondary wheel(s) or stabilizers to limit tilting about the primary axis, there is a potential problem of a child moving about in the seat when the pushchair is stationary causing it to rock back and forth about the primary axis. This could be unsettling to the child and in an extreme case might lead to backward and forward oscillation that compromises the overall stability of the stationary pushchair.
According to the present invention there is provided a pushchair of the type which comprises a chassis which is born upon one or more primary wheels on a primary wheel bearing axis, the chassis further having one or more forward and/or rear secondary wheel(s) or stabilizer(s) that in normal use of the pushchair during horizontal travel is/are not ground engaging but which limit tilting of the pushchair about the primary axis, the pushchair being characterized in that it further comprises a selectively operable stabilizer means which may be deployed to bring a prop means into ground engagement to substantially prevent tilting of the pushchair about the primary wheel axis when the pushchair is stationary.
In one preferred embodiment, the forward or rear secondary wheel(s) or stabilizers is/are selectively operable to be deployed to move into ground engagement when the pushchair is stationary.
The stabilizer means may comprise an adjustment mechanism whereby the chassis may be lowered relative to the primary wheel axis to bring the forward or rear secondary wheel(s) or stabilizer(s) into ground engagement.
In such arrangement lowering of the chassis may also bring a brake block into contact with the primary wheel(s). This is particularly advantageous since it enables operation of the stabilizing mechanism to be effected simultaneously with braking, greatly simplifying the actions involved in parking of the pushchair.
In an alternative embodiment of the present invention, the selectively operable stabilizer means may comprise an independent prop means that is mounted to the chassis and moveable from a stowed position adjacent the chassis to an extended position in which it props the chassis against tilting about the primary axis. Such a prop may also be adapted to engage the pushchair primary wheel(s) to simultaneously function as a brake.
Preferably in each of he above embodiments he selective operation of the selectively operable stabilizer means is effected by operation of a hand or foot operable lever which is mounted to the chassis of the pushchair. Such lever is preferably pivotally mounted to the chassis of the pushchair.